High Pressure Vises

I rarely use a vise, I never liked the way any of them hold parts. Michael

Michael:

What? How can you be a real machine shop without having a Chinese Kurt Knock Off vise laying around somewhere? LOL

You know kurt makes their D series and then a high(er) precision series -- P or S or sumpn.

Has anyone used these, noticed a diff between the two?

What's the price diff? Sheeit, the D's are already steep! Are the higher precision ones "worth it"?

Also, ito force, the D series already gets up to 8,000 #, so 17 would be about double.

What situation would require 17,000# worth of holding, in a 6" vise?

Also, easy enough to increase force without getting fancy-shmancy-- just use a finer thread lead screw -- mebbe with an electric or air ratchet, for speed.

PV:

Kurt's PT series of vises are called High Precision.

=======================================================

Available in 4"or 8" Models Available in Manual or Hydraulic Operation. "Pull-Type" clamping means high precision and repeatability. Up to 20,000 lbs. precision clamping force. Can be mounted upright or on either side. CNC style allows compact spacing. Both sides ground square to within 0.001" with base and top.

80,000 PSI ductile iron body. Hydraulic option is available as complete package. 10 Year Limited Warranty. Options Matching of bed height +_ 0.001" available at an additional cost. Matching of the keyway to the stationary jaw +_0.001" available at an additional cost. Hand or Foot Intensifier =======================================================

The 4" PT is about $1,200. The D688 is about $568.

The possible problem with that solution is that with enough force on the screw you can actually distort the base, and the key/keway in the immovable jaw.

I dislike vises for several reasons, one, you have a fixed jaw and a moving jaw. Keeping a part perp isn't exactly possible. Any amount of clearance to allow movement of one side inserts a variable into the perpendicularity scenario. As the one moving jaw tightens, the clearance in that jaw (which increases with the amount of wear on the device) allows a part to flop a certain amount, the tighter you force the moving jaw into the fixed jaw, the "clearance" shifts even more. Boring vise jaws still does the same thing. Vise jaws are a last resort.

Coming from a mold and pattern background, I insert dowels into the back of a part, drill and tap hold down points and then drill a matching subplate to mount the part onto. Bolt that subplate onto a flat cnc table surface and bolt or clamp down as evenly and equally as possible. Then machine without obstructions around the part, you can cut into the subplate where it needs to be cut to get the tangency point of ball end mills to their proper depths to achieve full diameter cuts. Here is a link to show the back side of some pattern pieces with the bolt and dowels in the work piece. By placing the dowels in the proper places, remounting the piece at some later date is easily done, the XY zero points can be located exactly between the dowel locating pins. Even with a worn part, the XY zero feature never gets obscured or lost, even if a part has been welded up after long runs make the part worn. This makes setup and reset up a simple operation vs guessing where a feature used to be to get aligned.

1st image: is the wood part the gray iron casting blanks were derived from. 2nd image: the dowel/hold down location setups for machining the pattern and for mounting the finished tools 3rd image: several ready to be machined 4th image: as you can see, the machining and the production pattern mounting scheme holes are all put into a work piece in a single setup, so no alignment mistakes will ever happen. 5th image: being machine on a cheese plate 6th image: finished parts 7th image: finish part benched out, ready for production Surely you vise guys don't go back ad attempt to add mounting and alignment holes after the part is machined? Setup and alignment are one operation, not some easy vise holding ops plus drilling ops done later? That is where shift comes from, for perfect alignment there is much more than a vise operation to be considered.

Of course if you are machining tiny parts a vise may be required, even then there are other ways to do things than with a vise.

Michael

We've got quite a few of the 6 inch D models, and they are all within .002" of each other when checking the height from one to the next. Good enough for vise parts.

Later,

Charlie

Michael:

You know, if you were talking about the vises in use during my apprenticeship you would be absolutely correct. But Kurt, and Kurt copies are designed in such a way that for every pound of CLOSING force there is a half-pound of DOWNWARD force. (At least that's what they've been advertising for decades). Let me go search for a pic of the internals:

==============================================================

The patented Anglock design allows the movable jaw to advance in such a way that each pound of force forward induces a ½ pound force downward which minimizes the jaw lift and increases accuracy. This combined with the needle bearings increases jaw clamping pressure. Other features include: 80,000 psi ductile iron body, hardened vise bed & jaw plates, semi-hard steel screw. ==============================================================

So even when they wear - the movable jaw is still held down under clamping pressure. And when boring or machining soft jaws, you always clamp against a spacer so the jaw is held down - just like when it will be clamping your part.

Nice work! And obviously not all parts lend themselves to vise work, but to rule out vises for ALL work is IMO, limiting your options.

If you're machining something on all 6 sides, then you have to determine what you'll use for your locating datums. It could be the edge, prior machined features, part holes, or extra material you've left just for that purpose.

Yes, there is more than one way to shave a cat, BUT - you don't want to pull the fur out one strand at a time - when you can use a razor or Nair. LOL

I can buy a D75 for $385.

People banging on them with hammers and cheaters are idiots, period.

If your parts are coming out of a Kurt vise, you have tooling/setup issues.

Machining is an industry that's filled with idiots. One of these idiots has well over 20 years worth of machining experience and is / was stupid enough to work for $23 an hour for a moron boss who buys cheap Chinese Kurt knock off vises at an auction and thinks he got a bargain.

Jon Banquer San Diego, CA

Sounds cool as long as you can repeat the pressure somehow.

You're living proof of that.

Barn

I specifically did not rull out ALL vises or all situations. Regardless of claims, patents, sales pitches etc, put an indicator on parts clamped in a vise of any description and watch the parts move. As for that 80,000 psi rating, what about parts being bent out of round? Sheer pressure ratings go poof when the parts are not always solid plugs. Delicate thin walled parts will be crushed and bent out of round with anywhere close to that pressure, even when soft jaws are bored.. I have bored many many sets of soft jaws but still they never pass the indicator test, the parts being held all move to some degree.

I often use tabs to hold parts, they can always be removed afterwards. My new cnc will have a trunnion and rotary axis to rotate parts and machine the different sides. It arrives Tuesday morning at 8am. Michael

Arnold Workholding?s high-pressure vises are available in a number of manual and automatic versions offering maximum clamping forces from

5,500 to 17,600 pounds

what? On a 1/2 lb part, isn't 5,500 to 17,600 lbs of clamping force possibly a bit of over kill? I bet aluminum pistons or brass cylinder parts do well under that much pressure. How about brass sealing rings? max pressure again?

Sales pitches are not always applicable to every application in machine shops. Michael

But if you need to crack a coconut...

Michael:

Then we're copacetic.

Yes, metal moves like silly putty under enough pressure. If when using a vise your parts move more than you can adjust for and still make good parts, then you try another option.

The 80,000 psi figure was for the ductile iron body/frame, not the clamping force.

I've sometimes used the one finger clamping method, and even the inch pound torque wrench method, and I've used the "make a plug to keep the part from crushing method". But like I said, ALL parts don't lend themselves to vise usage. Just as ALL parts don't lend themselves to subplate usage.

Tabs, Chocolate Chipping, super-glue, double back tape, Cerobend, clamps, screws, Mitee-Bites, dovetail holders, etc. etc. There are many ways to hold parts.

Hey, that's pretty cool. What kind is it? Must have gotten a real deal in this buyers market, eh?

Michael:

That's the MAXIMUM clamping force the vise can produce. No one says you HAVE to use the maximum clamping force for watch parts, eh.

Cliff is available for employment if you have a copy of Jurassic-CAD/CAM.

Warning!

Unless you want to collect on your insurance don't let Cliff write any g-code himself. So far Cliff averages five mistakes per radius with his C-CRAP (Cliffs-Center of Radius Approach to Programming) method.

So when you C-CRAP you know Cliff did it.

Tom

Bob, I'll make all my replies in one place for simplicity. The new cnc is a Haas VM2, it lists for just over 100k, basically Haas is paying for 1/4th of the machine by giving us an approximate 25% discount. If they, Haas, are willing to pay for 25% of the machine we'll take that!

I think we got a great deal with all the optional stuff, yes, I'm good with it. One thing that is different is that I am forming an s-corp, "South Georgia MicroSystems" built a new building behind my home and am putting this machine right here so I can get back into machining much of my own work. Actually, I have been making silicone medical molds and getting the setup info across to other folks at the shop is tough on these molds. LSR molds have to be perfect, anything less than total focus on the setup won't cut it. So, like I always heard, if you want something done right just do it yourself. So that is exactly what I have done. Medical mold setup is a bit more intricate than foundry sand casting setups. I fully trust myself to do this right.

I was fortunate in the electrical setup, my power company put me in a dedicated transformer, we are using a rotary converter to reach 3 phase. All that was finished a while back. fwiw, I live outside the city and out of the city regulations so that too is all good.

About the images I posted, I have waited several days on purpose to see who would ask how I held those huge castings to machine the bolt, dowel and cobore ops in the castings. I have been waiting but nobody asked, I held the castings in a huge vise, lol! That is why I initially inserted a disclaimer that I "almost" never use a vise. I like sparring, poking fun and such, dang it, nobody figured it out.

One other thing about holding small parts, don't forget vacuum tables. Michael

lol! Michael